Postoperative Morbidity and Mortality in Patients with End-Stage Renal Disease Undergoing Free Flap Reconstruction of the Head and Neck

Postoperative Morbidity and Mortality in Patients with End-Stage Renal Disease Undergoing Free Flap Reconstruction of the Head and Neck | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Postoperative Morbidity and Mortality in Patients with End-Stage Renal Disease Undergoing Free Flap Reconstruction of the Head and Neck Uttsav Patel, Anisha Javvaji, Adam Daniels, Christopher Vanison This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7808587/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 25 Feb, 2026 Read the published version in European Journal of Plastic Surgery → Version 1 posted 7 You are reading this latest preprint version Abstract Background Relatively little data exists regarding the ways in which end-stage renal disease (ESRD) affects microvascular surgery outcomes. This study sought to identify whether ESRD was an independent predictor of 30-day postoperative complication and readmission rates after head & neck free flap reconstruction. Methods The TriNetX database was used to identify individuals who underwent head and neck free flap reconstruction between 2014 and 2023. Two cohorts were created based on whether or not patients had ESRD. Propensity score matching based on demographics and relevant comorbidities was performed. Differences in 30-day complication and readmission rates were then compared between cohorts. Results After propensity matching was performed, ESRD patients were noted to have significantly higher risks of deep vein thrombosis (aRR 2.308, p = 0.008), myocardial infarction (aRR 2.005, p = 0.045), pneumonia (aRR 1.897, p < 0.001), anemia (aRR 1.452, p = 0.011), skin graft-associated complications (aRR 2.900, p = 0.002), fluid overload (aRR 1.862, p = 0.043) and mortality (aRR 2.200, p = 0.030). Compared to controls, ESRD patients had a lower likelihood of readmission (aRR 0.630, p = 0.024). Conclusions This study demonstrated that ESRD can significantly influence several early postoperative outcomes of head and neck free flap surgery when controlling for demographics and other comorbidities. Level of Evidence: Level III, risk study Head and neck cancer Free flap reconstruction Outcome studies Complications Head and neck reconstruction Figures Figure 1 Figure 2 Introduction Free flap reconstruction has become the standard of care to address large head and neck (H&N) defects, effectively restoring both appearance and function in areas of large tissue loss [ 1 ]. The current survival rate of free flaps in H&N surgery is around 95–99% [ 2 ]. While flap survival outcomes are excellent, postoperative morbidity is common, affecting up to 30–71% of patients [ 2 ]. Patients with end-stage renal disease (ESRD) have a higher incidence of malignancy compared to the general population, and approximately 7% of dialysis patients will develop H&N cancer [ 3 ]. This may pose reconstructive challenges after major extirpative surgeries as ESRD patients often have multiple comorbid conditions which may impact outcomes. Renal failure itself leads to a buildup of uremic toxins which can also impair local mechanisms of wound healing [ 4 ]. Therefore, evaluating whether ESRD patients have worse health outcomes following H&N free flap surgery is of importance. There is a relatively limited body of research investigating outcomes of free tissue transfer in renal failure patients [ 5 ]. Among these studies, results are somewhat conflicting. While some studies report no difference in flap success rates, others such as Oglesby et al found significant differences between cohorts but utilized a limited selection of matched variables [ 5 , 6 ]. Our study aimed to advance current understanding by matching for a broader range of comorbidities with a larger sample size, in effort to isolate ESRD as an independent factor affecting postoperative outcomes after H&N free flap reconstruction. Materials and Methods This retrospective cohort study utilized the TriNetX Research Network (with NLP), including 113,186,557 patients aged 18 and older, to identify individuals with H&N cancers who underwent free flap reconstruction. H&N cancer patients were identified using ICD-10 codes: C00, C01, C02, C03, C04, C05, C06., C07., C08, C09., C10, C11, C12, C13, C14, C30, C31 and C32. Free flap reconstruction was identified using Current Procedural Terminology (CPT) codes 15756, 15757, 15758, 20955, 20956, 20969, and 20970. Patients under age 18 were excluded from this study. The population was stratified into two groups based on the presence or absence of ESRD. The study cohort included patients who had ESRD at the time of surgery, as indicated by ICD-10 codes I12.0, I13.11, I13.2, N81.5, N81.6, Z99.2, or CPT code 1012740. The control cohort consisted of patients who had no documented history of ESRD or dialysis prior to the index surgery event. Data extracted included patient demographics, preoperative comorbidities, and 30-day postoperative morbidity and mortality. Demographics encompassed age at time of surgery, race, ethnicity, and gender. Preoperative comorbidities included type 2 diabetes, hyperlipidemia, hypertension, congestive heart failure (CHF), obesity, chronic obstructive pulmonary disease (COPD), liver disease, sleep disorders, smoking, alcoholism, anemia, and coagulation disorders. The ESRD and non-ESRD cohorts were propensity-matched at a 1:1 ratio based on significant demographics and comorbidities (Fig. 1 ). Postoperative outcomes were analyzed within a 30-day window after surgery. Outcomes included surgical site infections (SSI), wound dehiscence, skin graft-related complications, sepsis, deep vein thrombosis (DVT), pulmonary embolism (PE), stroke, myocardial infarction (MI), sudden cardiac death, pneumonia, urinary tract infections (UTI), need for transfusion, anemia, postprocedural hemorrhage, aspiration, delirium, vasopressor use, fluid overload, readmission, reoperation and mortality. Complications with fewer than 10 occurrences were excluded due to insufficient data for accurate analysis. All statistical analyses were conducted within the TriNetX platform, using adjusted risk ratios with 95% confidence intervals (CI) after propensity matching. Statistical significance was assigned as p ≤ 0.05. Results Among approximately 113 million patients across 94 health care organizations in the TriNetX database, 393 patients with ESRD and 14,476 patients without ESRD underwent free flap reconstruction of H&N cancer extirpative defects. Prior to propensity score matching, there were significant differences observed between the two cohorts in their demographics and preoperative comorbidities, including gender, type 2 diabetes mellitus, hyperlipidemia, hypertension, congestive heart failure (CHF), obesity, chronic obstructive pulmonary disease (COPD), liver disease, sleep disorders, smoking, alcoholism, anemia, and coagulation disorders (Table 1 ). Table 1 Characteristics of ESRD and non-ESRD Before Propensity Score Matching Number (%) Risk Factor ESRD Non-ESRD p- value Age at Index 387 (63.9 ± 11.0) 14,123 (62.8 ± 12.1) 0.0.67 Male 283 (81.1%) 9,408 (66.6%) 0.007 Type 2 Diabetes Mellitus 188 (48.6%) 2,214 (15.7%) < 0.001 Hyperlipidemia 209 (54.0%) 3,265 (23.1%) < 0.001 Hypertension 312 (80.6%) 6,669 (47.2%) < 0.001 Heart Failure 82 (21.1%) 506 (3.6%) < 0.001 Obesity 93 (24.0%) 1,153 (8.2%) < 0.001 Chronic Obstructive Pulmonary Disease 153 (39.5%) 3,270 (23.2%) < 0.001 Liver Disease 92 (23.8%) 1,114 (7.9%) < 0.001 Sleep Disorders 147 (38.0%) 1,738 (12.3%) < 0.001 Smoking 166 (42.9%) 3,801 (26.9%) < 0.001 Alcoholism 92 (23.8%) 1,582 (11.2%) < 0.001 Anemia 157 (40.6%) 1,670 (11.8%) < 0.001 Coagulation Disorders 111 (28.7%) 884 (6.3%) < 0.001 After propensity score matching, the cohorts each consisted of 386 patients, and the significant differences in demographics and comorbidities were no longer present (Table 2 ). Table 2 Characteristics of ESRD and Non-ESRD After Propensity Score Matching Number (%) Risk Factor ESRD Non-ESRD p- value Age at Index 386 (63.9 ± 11.0) 386 (63.6 ± 11.3) 0.679 Male 282 (73.1%) 273 (70.7%) 0.471 Type 2 Diabetes Mellitus 187 (48.4%) 188 (48.7%) 0.943 Hyperlipidemia 208 (53.9%) 213 (55.2%) 0.718 Hypertension 311 (80.6%) 316 (81.9%) 0.645 Heart Failure 81 (21.0%) 73 (18.9%) 0.471 Obesity 92 (23.8%) 110 (28.5%) 0.141 Chronic Obstructive Pulmonary Disease 152 (39.4%) 153 (39.6%) 0.941 Liver Disease 91 (23.6%) 87 (22.5%) 0.732 Sleep Disorders 146 (37.8%) 153 (39.6%) 0.605 Smoking 166 (43.0%) 163 (42.2%) 0.827 Alcoholism 91 (22.6%) 85 (22.0%) 0.607 Anemia 156 (40.4%) 162 (42.0%) 0.661 Coagulation Disorders 110 (28.5%) 99 (25.6%) 0.373 During the 30-day postoperative period, the rate of occurrence of several outcomes was significantly different between cohorts (Table 3 ). Most notably, ESRD patients had significantly higher risk of pneumonia (aRR: 1.897, 95% CI: 1.322–2.723, p < 0.001), skin graft-related complications (aRR: 2.900, 95% CI: 1.433–5.868, p = 0.002) and DVT (aRR: 2.308, 95% CI: 1.223–4.356, p = 0.008). Other outcomes which were significantly more common in the ESRD group included anemia (aRR: 1.452, 95% CI: 1.085–1.942, p = 0.011), fluid overload (aRR: 1.862, 95% CI: 1.145–3.182, p = 0.043) and MI (aRR: 2.005, 95% CI: 1.015–4.225, p = 0.045). Mortality rates were significantly higher in the ESRD group (aRR: 2.200, 95% CI: 1.056–4.584, p = 0.030). Interestingly, ESRD patients had a lower likelihood of readmission during the 30-day postoperative period (aRR: 0.630, 95% CI: 0.420–0.944, p = 0.024). Table 3 Post-operative complications in ESRD and Non-ESRD Patients Number (%) ESRD Non-ESRD Adjusted Risk Ratio (95% CI) p- value Surgical Site Infection 15 (3.9%) 13 (3.4%) 1.154 (0.557 to 2.392) 0.700 Wound Dehiscence 40 (10.4%) 43 (11.1%) 0.930 (0.619 to 1.397) 0.727 Deep Vein Thrombosis 30 (7.8%) 13 (3.4%) 2.308 (1.223 to 4.356) 0.008 Pulmonary Embolism 14 (3.6%) 12 (3.1%) 1.167 (0.547 to 2.490) 0.690 Stroke 35 (9.1%) 26 (6.7%) 1.346 (0.827 to 2.192) 0.230 Myocardial Infarction 25 (6.5%) 11 (2.9%) 2.005 (1.015 to 4.225) 0.045 Pneumonia 74 (19.2%) 39 (10.1%) 1.897 (1.322 to 2.723) < 0.001 Transfusions 120 (31.1%) 130 (33.7%) 0.923 (0.753 to 1.132) 0.442 Postoperative Anemia 90 (23.3%) 62 (16.1%) 1.452 (1.085 to 1.942) 0.011 Skin Graft Complications 29 (7.5%) 10 (2.6%) 2.900 (1.433 to 5.868) 0.002 Vasopressor Use 102 (26.4%) 83 (21.5%) 1.229 (0.954 to 1.583) 0.109 Fluid Overload 30 (7.8%) 16 (4.1%) 1.862 (1.145 to 3.182) 0.043 Readmission 34 (8.8%) 54 (14.0%) 0.630 (0.420 to 0.944) 0.024 Reoperation 11 (2.9%) 10 (2.6%) 1.100 (0.473 to 2.560) 0.825 Mortality 22 (5.7%) 10 (2.6%) 2.200 (1.056 to 4.584) 0.030 No significant differences were observed between cohorts for SSI ( p = 0.700), wound dehiscence ( p = 0.727), pulmonary embolism ( p = 0.690), vasopressor requirements ( p = 0.109), transfusion requirements ( p = 0.442) and need for reoperation ( p = 0.825). (Fig. 2 ) Sepsis, postprocedural hemorrhage, sudden cardiac death, flap failure, aspiration, delirium, and urinary tract infection (UTI) were rare, affecting fewer than ten patients in each group. Due to their low incidences, these complications did not provide sufficient data for risk ratio calculations. Discussion Our study focused on identifying ESRD as an independent cause of postoperative morbidity and mortality, as limited data exists on this subject. During the 30-day postoperative period, patients with ESRD had significantly higher rates of DVT, MI, pneumonia, anemia, skin graft-related complications, fluid overload, and mortality. The effect of ESRD on DVT and MI risks may be explained by endothelial dysfunction caused by chronic kidney disease, which may lead to thrombotic events [ 7 ]. The mechanisms of a prothrombotic state in ESRD remain unclear, but previous studies have shown that venous thromboembolism events are doubled in this population [ 8 ]. Biben et al. reported that a hypercoagulable state is not a contraindication for free flap procedures but advised the use of a thromboprophylaxis regimen [ 9 ]. The higher rate of postoperative pneumonia in the ESRD cohort aligns with previous studies, which show that patients with chronic renal failure are inherently immunocompromised and are therefore more prone to infection [ 10 ]. These patients may be more susceptible to developing pneumonia both from in-hospital microbial exposures or from aspiration. Fluid overload is a common issue faced by patients with ESRD. Persistent fluid overload can lead to hypertension, pulmonary edema, and congestive heart failure, increasing the risk of mortality [ 11 ]. Similarly, fluid overload intraoperatively and on postoperative day one have been shown to increase complication rates after microvascular surgery [ 12 ]. Fluid overload in the immediate perioperative period poses a significant threat to flap viability [ 13 ]. During lengthy surgeries such as H&N free flap reconstruction, intraoperative fluid management may be particularly difficult in patients with severely reduced or no renal function. Lack of urine output may make postoperative fluid balance monitoring difficult between dialysis treatments. Efforts to maintain net zero fluid status may be influenced by institutional or surgeon-based preferences regarding use of vasopressors versus volume replacement in response to changes in vital signs. Postoperative anemia in patients with ESRD is influenced by reduced erythropoietin production [ 14 ]. H&N free flap reconstructive surgeries may lead to significant intraoperative blood loss, and patients with renal dysfunction are less equipped to restore red blood cell volume. There is data which shows that this postoperative anemia in ESRD patients directly affects mortality [ 14 ]. An unexpected finding from this study was that patients in the non-ESRD group were significantly more likely to be re-admitted during the 30-day postoperative period. This result differs from reports that ESRD patients typically have higher rates of readmission compared to the general population [ 15 ]. One important data point that was unavailable to us in this study was length of admission after surgery. It is possible that, with the higher rate of significant complications, ESRD patients remained in the hospital for longer than the non-ESRD patients. This would be corroborated by the findings of Manrique and colleagues [ 16 ]. Earlier discharge may allow for more opportunity for re-admission during this time. Data is not available regarding whether certain patients in our cohorts were transferred to subacute or long-term acute care facilities after hospitalization and if that may have influenced readmission rates. In our study, flap failure was a rare occurrence in both cohorts. However, this was only able to be extrapolated upon by identifying patients who required a second free tissue transfer during the 30-day postoperative window. This demonstrates an inherent challenge of using TriNetX as there is no unique ICD 10 code for free flap failure. By using a surrogate grouping of codes, we may have underestimated or overestimated the number of flap failures. Existing literature shows mixed results on free flap success rates in patients with ESRD. Oglesby et al found that, when compared to matched controls, there was a significantly increased risk of flap failure in CKD patients as well as a significantly increased risk of overall complications [ 5 ]. This study evaluated a relatively small cohort, controlled for few variables such as flap type, age, gender, and cancer stage, and did not control for other medical comorbidities. Manrique et al. also found that ESRD patients were at higher risk of postoperative complications, 30-day mortality, and longer hospital stays, likely due to comorbidities like peripheral vascular disease (PVD) and diabetes [ 16 ]. Our finding was similar to Hung et al., who showed that there was no difference in take-back rates, or reoperation rate, between dialysis and non-dialysis patients in their study [ 6 ]. Although we performed propensity matching for multiple comorbidities in attempt to identify ESRD as an independent risk factor, different causes of ESRD itself may have influenced outcomes. For example, Moran et al. found that patients with renal failure associated with diabetes had significantly higher complication rates after free tissue transfer than ESRD patients without diabetes (93% vs. 20%) [ 17 ]. While renal disease itself seems to be associated with increased complication rates after H&N reconstruction, it may be that the interplay of ESRD and the underlying causative condition(s) may also be important. Future studies should include patients with different stages of chronic kidney disease or should specify dialysis dependency to assess their distinct impacts on free flap outcomes and complications. In addition, future prospective studies are needed to validate these findings and could provide more granular data on the impact of intraoperative fluid management and dialysis scheduling on free flap outcomes. Conclusion Our study demonstrated that ESRD is an independent risk factor for DVT, MI, pneumonia, anemia, skin graft-related complications, fluid overload, and mortality during the 30-days postoperative period after H&N free flap reconstruction. For unclear reasons, readmission rates were higher among patients without ESRD. Prospective data will be important to corroborate and provide further understanding regarding these findings. Declarations Competing Interests: The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article. Funding Statement: The authors received no financial support for the research, authorship and/or publication of this article. Ethical Approval and Informed Consent Statement: The ethics review committee of Stony Brook Medicine waived the need for ethics approval and patient consent for the collection, analysis and publication of the retrospectively obtained and anonymized data for this non-interventional study. Data Availability Statement: The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request. Author Contributions: All authors contributed to the study conception and design. Data analysis was performed by anonymous. All authors contributed to the writing of the manuscript, and all authors read and approved the final manuscript. References Gabrysz-Forget F, Tabet P, Rahal A, Bissada E, Christopoulos A, Ayad T Free versus pedicled flaps for reconstruction of head and neck cancer defects: a systematic review. [published online March 14, 2019]. J Otolaryngol – Head Neck Surg 10.1186/s40463-019-0334-y Jeong B, Lynch N, Hodge J, Boase S, Valentine R, Krishnan S, Foreman A Single service otolaryngology head and neck surgery free flap reconstruction of head and neck ablative defects – a retrospective single centre review of our initial 6-year experience. [published online January 26, 2024]. 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J Cardiothorac Vasc Anesth 31(6):2251–2267 Yu S, Wei K, Zhou D, Lin Q, Li T Predictive factors of postoperative complications related to free flap reconstruction in head and neck cancer patients admitted to intensive care unit: a retrospective cohort study. [published online July 29, 2024]. BMC Anesthesiol 10.1186/s12871-024-02649-9 Burkhard J, Pfister J, Giger R, Huber M, Landrach C, Waser M, Olariu R, Engel D, Loffel LM, Schaller B, Wuethrich PY (2021) Perioperative predictors of early surgical revision of flap-related complications after microvascular free tissue transfer in head and neck reconstructions: a retrospective observational series. Clin Oral Investig 25(9):5541–5550 Hain D, Bednarski D, Cahill M, Dix A, Foote B, Haras MS, Pace R, Gutierrez OM Iron-deficiency anemia in CKD: a narrative review for the kidney care team. [published online May 25, 2023]. Kidney Med 10.1016/j.xkme.2023.100677 Mathew AT, Strippoli GF, Ruospo M, Fishbane S (2015) Reducing hospital readmissions in patients with end-stage kidney disease. Kidney Int 88(6):1250–1260 Manrique OJ, Ciudad P, Sharaf B, Martinez-Jorge J, Moran S, Mardini S, Chen HC, Bite U, Cheng HT (2017) Free tissue transfers for head and neck reconstruction in patients with end-stage renal disease on dialysis: analysis of outcomes using the Taiwan National Health Insurance Research Database. J Reconstr Microsurg 33(8):587–591 Moran SL, Salgado CJ, Serletti JM (2004) Free tissue transfer in patients with renal disease. Plast Reconstr Surg 113:2006–2011 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 25 Feb, 2026 Read the published version in European Journal of Plastic Surgery → Version 1 posted Editorial decision: Revision requested 23 Nov, 2025 Reviews received at journal 20 Nov, 2025 Reviewers agreed at journal 19 Oct, 2025 Reviewers invited by journal 17 Oct, 2025 Editor assigned by journal 08 Oct, 2025 Submission checks completed at journal 08 Oct, 2025 First submitted to journal 08 Oct, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7808587","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":531912673,"identity":"d464bb29-1cca-4a12-aea3-f53265f40ed3","order_by":0,"name":"Uttsav 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01:39:47","extension":"jpeg","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":405736,"visible":true,"origin":"","legend":"","description":"","filename":"PatelFig1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/7784b80c96acf19074211d27.jpeg"},{"id":94806722,"identity":"80d8951b-875a-4816-929f-bf7d1de6cc1a","added_by":"auto","created_at":"2025-10-31 01:39:47","extension":"jpeg","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":298335,"visible":true,"origin":"","legend":"","description":"","filename":"PatelFigure2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/f46a78b40d49eea14ff29703.jpeg"},{"id":94806640,"identity":"086ab363-6978-4acf-b827-7bbf9e5b32b2","added_by":"auto","created_at":"2025-10-31 01:39:42","extension":"jpeg","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":185079,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/7239b857976a056a1314484d.jpeg"},{"id":94806684,"identity":"12a11e23-f328-4e71-bf88-13a483554006","added_by":"auto","created_at":"2025-10-31 01:39:45","extension":"jpeg","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":126644,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/40f02953080a77bc76ab3d66.jpeg"},{"id":94806635,"identity":"27d7336f-e0d9-486c-95b1-65b3a1c67124","added_by":"auto","created_at":"2025-10-31 01:39:42","extension":"png","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":287432,"visible":true,"origin":"","legend":"","description":"","filename":"OnlinePatelFig1.png","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/d6e049b19c70054bfdb61316.png"},{"id":94806674,"identity":"e4f69dcf-2b81-43d4-8e7f-9b86ab696cba","added_by":"auto","created_at":"2025-10-31 01:39:44","extension":"png","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":364656,"visible":true,"origin":"","legend":"","description":"","filename":"OnlinePatelFigure2.png","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/7d108db6f867725f3f870bfc.png"},{"id":94806660,"identity":"ebca6054-19f1-4617-8349-698e85f826bf","added_by":"auto","created_at":"2025-10-31 01:39:43","extension":"png","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":114478,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/78987367c1fdc149edb31ff3.png"},{"id":94806669,"identity":"6b5d7f7a-c939-4737-af27-e179c35f6455","added_by":"auto","created_at":"2025-10-31 01:39:44","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":111528,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/e1eb6d6bfce85d24a59fe871.png"},{"id":94806704,"identity":"425cc0a6-c8ff-4ee4-b4d4-c44f037b70ff","added_by":"auto","created_at":"2025-10-31 01:39:46","extension":"xml","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":71443,"visible":true,"origin":"","legend":"","description":"","filename":"d2c840f6891c487c9f6a9df2707f13441structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/7e902e24001f1e6d0dcb04f7.xml"},{"id":94806688,"identity":"126550a9-6712-4cb6-8fad-70d74aed2c85","added_by":"auto","created_at":"2025-10-31 01:39:45","extension":"html","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":77883,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/535a2196f2f28294cb99834c.html"},{"id":94806644,"identity":"94d5cf37-f0a6-48ec-8617-6dd0e9d0d769","added_by":"auto","created_at":"2025-10-31 01:39:42","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":405736,"visible":true,"origin":"","legend":"\u003cp\u003eA flowchart demonstrating the patient selection process from the TriNetX Research Network.\u003c/p\u003e","description":"","filename":"PatelFig1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/efa864e69cd10fb5e7e257b4.jpeg"},{"id":94806706,"identity":"59f290c5-b6b0-4028-aa4e-1c07db3d8d84","added_by":"auto","created_at":"2025-10-31 01:39:46","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":298335,"visible":true,"origin":"","legend":"\u003cp\u003eA forest plot showing the adjusted risk ratios for postoperative complications in ESRD versus non-ESRD patients\u003c/p\u003e","description":"","filename":"PatelFigure2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/15efcec5638be51465652336.jpeg"},{"id":103766428,"identity":"c61537bd-2114-4c11-9e7d-f885cbfb2510","added_by":"auto","created_at":"2026-03-02 16:14:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1232171,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7808587/v1/8c907282-a068-4551-8163-ad7503416c5a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Postoperative Morbidity and Mortality in Patients with End-Stage Renal Disease Undergoing Free Flap Reconstruction of the Head and Neck","fulltext":[{"header":"Introduction","content":"\u003cp\u003eFree flap reconstruction has become the standard of care to address large head and neck (H\u0026amp;N) defects, effectively restoring both appearance and function in areas of large tissue loss [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The current survival rate of free flaps in H\u0026amp;N surgery is around 95\u0026ndash;99% [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. While flap survival outcomes are excellent, postoperative morbidity is common, affecting up to 30\u0026ndash;71% of patients [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e\u003cp\u003ePatients with end-stage renal disease (ESRD) have a higher incidence of malignancy compared to the general population, and approximately 7% of dialysis patients will develop H\u0026amp;N cancer [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. This may pose reconstructive challenges after major extirpative surgeries as ESRD patients often have multiple comorbid conditions which may impact outcomes. Renal failure itself leads to a buildup of uremic toxins which can also impair local mechanisms of wound healing [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Therefore, evaluating whether ESRD patients have worse health outcomes following H\u0026amp;N free flap surgery is of importance.\u003c/p\u003e\u003cp\u003eThere is a relatively limited body of research investigating outcomes of free tissue transfer in renal failure patients [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Among these studies, results are somewhat conflicting. While some studies report no difference in flap success rates, others such as Oglesby et al found significant differences between cohorts but utilized a limited selection of matched variables [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Our study aimed to advance current understanding by matching for a broader range of comorbidities with a larger sample size, in effort to isolate ESRD as an independent factor affecting postoperative outcomes after H\u0026amp;N free flap reconstruction.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eThis retrospective cohort study utilized the TriNetX Research Network (with NLP), including 113,186,557 patients aged 18 and older, to identify individuals with H\u0026amp;N cancers who underwent free flap reconstruction. H\u0026amp;N cancer patients were identified using ICD-10 codes: C00, C01, C02, C03, C04, C05, C06., C07., C08, C09., C10, C11, C12, C13, C14, C30, C31 and C32. Free flap reconstruction was identified using Current Procedural Terminology (CPT) codes 15756, 15757, 15758, 20955, 20956, 20969, and 20970. Patients under age 18 were excluded from this study.\u003c/p\u003e\u003cp\u003eThe population was stratified into two groups based on the presence or absence of ESRD. The study cohort included patients who had ESRD at the time of surgery, as indicated by ICD-10 codes I12.0, I13.11, I13.2, N81.5, N81.6, Z99.2, or CPT code 1012740. The control cohort consisted of patients who had no documented history of ESRD or dialysis prior to the index surgery event.\u003c/p\u003e\u003cp\u003eData extracted included patient demographics, preoperative comorbidities, and 30-day postoperative morbidity and mortality. Demographics encompassed age at time of surgery, race, ethnicity, and gender. Preoperative comorbidities included type 2 diabetes, hyperlipidemia, hypertension, congestive heart failure (CHF), obesity, chronic obstructive pulmonary disease (COPD), liver disease, sleep disorders, smoking, alcoholism, anemia, and coagulation disorders. The ESRD and non-ESRD cohorts were propensity-matched at a 1:1 ratio based on significant demographics and comorbidities (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003ePostoperative outcomes were analyzed within a 30-day window after surgery. Outcomes included surgical site infections (SSI), wound dehiscence, skin graft-related complications, sepsis, deep vein thrombosis (DVT), pulmonary embolism (PE), stroke, myocardial infarction (MI), sudden cardiac death, pneumonia, urinary tract infections (UTI), need for transfusion, anemia, postprocedural hemorrhage, aspiration, delirium, vasopressor use, fluid overload, readmission, reoperation and mortality. Complications with fewer than 10 occurrences were excluded due to insufficient data for accurate analysis. All statistical analyses were conducted within the TriNetX platform, using adjusted risk ratios with 95% confidence intervals (CI) after propensity matching. Statistical significance was assigned as \u003cem\u003ep\u003c/em\u003e \u0026le; 0.05.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eAmong approximately 113\u0026nbsp;million patients across 94 health care organizations in the TriNetX database, 393 patients with ESRD and 14,476 patients without ESRD underwent free flap reconstruction of H\u0026amp;N cancer extirpative defects. Prior to propensity score matching, there were significant differences observed between the two cohorts in their demographics and preoperative comorbidities, including gender, type 2 diabetes mellitus, hyperlipidemia, hypertension, congestive heart failure (CHF), obesity, chronic obstructive pulmonary disease (COPD), liver disease, sleep disorders, smoking, alcoholism, anemia, and coagulation disorders (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCharacteristics of ESRD and non-ESRD Before Propensity Score Matching\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eNumber (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRisk Factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eESRD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNon-ESRD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003ep-\u003c/em\u003evalue\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge at Index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e387 (63.9\u0026thinsp;\u0026plusmn;\u0026thinsp;11.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14,123 (62.8\u0026thinsp;\u0026plusmn;\u0026thinsp;12.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.0.67\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e283 (81.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9,408 (66.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.007\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eType 2 Diabetes Mellitus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e188 (48.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2,214 (15.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHyperlipidemia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e209 (54.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3,265 (23.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypertension\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e312 (80.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6,669 (47.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHeart Failure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e82 (21.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e506 (3.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eObesity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e93 (24.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1,153 (8.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChronic Obstructive Pulmonary Disease\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e153 (39.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3,270 (23.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLiver Disease\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e92 (23.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1,114 (7.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSleep Disorders\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e147 (38.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1,738 (12.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSmoking\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e166 (42.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3,801 (26.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAlcoholism\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e92 (23.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1,582 (11.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAnemia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e157 (40.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1,670 (11.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCoagulation Disorders\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e111 (28.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e884 (6.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eAfter propensity score matching, the cohorts each consisted of 386 patients, and the significant differences in demographics and comorbidities were no longer present (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCharacteristics of ESRD and Non-ESRD After Propensity Score Matching\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eNumber (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRisk Factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eESRD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNon-ESRD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003ep-\u003c/em\u003evalue\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge at Index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e386 (63.9\u0026thinsp;\u0026plusmn;\u0026thinsp;11.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e386 (63.6\u0026thinsp;\u0026plusmn;\u0026thinsp;11.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.679\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e282 (73.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e273 (70.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.471\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eType 2 Diabetes Mellitus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e187 (48.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e188 (48.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.943\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHyperlipidemia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e208 (53.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e213 (55.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.718\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypertension\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e311 (80.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e316 (81.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.645\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHeart Failure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e81 (21.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e73 (18.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.471\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eObesity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e92 (23.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e110 (28.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.141\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChronic Obstructive Pulmonary Disease\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e152 (39.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e153 (39.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.941\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLiver Disease\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e91 (23.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e87 (22.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.732\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSleep Disorders\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e146 (37.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e153 (39.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.605\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSmoking\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e166 (43.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e163 (42.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.827\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAlcoholism\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e91 (22.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e85 (22.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.607\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAnemia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e156 (40.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e162 (42.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.661\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCoagulation Disorders\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e110 (28.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e99 (25.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.373\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eDuring the 30-day postoperative period, the rate of occurrence of several outcomes was significantly different between cohorts (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Most notably, ESRD patients had significantly higher risk of pneumonia (aRR: 1.897, 95% CI: 1.322\u0026ndash;2.723, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), skin graft-related complications (aRR: 2.900, 95% CI: 1.433\u0026ndash;5.868, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002) and DVT (aRR: 2.308, 95% CI: 1.223\u0026ndash;4.356, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008). Other outcomes which were significantly more common in the ESRD group included anemia (aRR: 1.452, 95% CI: 1.085\u0026ndash;1.942, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.011), fluid overload (aRR: 1.862, 95% CI: 1.145\u0026ndash;3.182, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.043) and MI (aRR: 2.005, 95% CI: 1.015\u0026ndash;4.225, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.045).\u003c/p\u003e\u003cp\u003eMortality rates were significantly higher in the ESRD group (aRR: 2.200, 95% CI: 1.056\u0026ndash;4.584, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.030). Interestingly, ESRD patients had a lower likelihood of readmission during the 30-day postoperative period (aRR: 0.630, 95% CI: 0.420\u0026ndash;0.944, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.024).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003e\u003cb\u003ePost-operative complications in ESRD and Non-ESRD Patients\u003c/b\u003e\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eNumber (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eESRD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNon-ESRD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAdjusted Risk Ratio (95% CI)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003ep-\u003c/em\u003evalue\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSurgical Site Infection\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e15 (3.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13 (3.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.154 (0.557 to 2.392)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.700\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWound Dehiscence\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e40 (10.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e43 (11.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.930 (0.619 to 1.397)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.727\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDeep Vein Thrombosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30 (7.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13 (3.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.308 (1.223 to 4.356)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.008\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePulmonary Embolism\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14 (3.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e12 (3.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.167 (0.547 to 2.490)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.690\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eStroke\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e35 (9.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e26 (6.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.346 (0.827 to 2.192)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.230\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMyocardial Infarction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e25 (6.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11 (2.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.005 (1.015 to 4.225)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.045\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePneumonia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e74 (19.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e39 (10.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.897 (1.322 to 2.723)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTransfusions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e120 (31.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e130 (33.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.923 (0.753 to 1.132)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.442\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePostoperative Anemia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e90 (23.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e62 (16.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.452 (1.085 to 1.942)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.011\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSkin Graft Complications\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e29 (7.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10 (2.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.900 (1.433 to 5.868)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.002\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVasopressor Use\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e102 (26.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e83 (21.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.229 (0.954 to 1.583)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.109\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFluid Overload\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30 (7.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e16 (4.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.862 (1.145 to 3.182)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.043\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eReadmission\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e34 (8.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e54 (14.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.630 (0.420 to 0.944)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.024\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eReoperation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11 (2.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10 (2.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.100 (0.473 to 2.560)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.825\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMortality\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e22 (5.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10 (2.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.200 (1.056 to 4.584)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.030\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eNo significant differences were observed between cohorts for SSI (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.700), wound dehiscence (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.727), pulmonary embolism (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.690), vasopressor requirements (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.109), transfusion requirements (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.442) and need for reoperation (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.825). (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eSepsis, postprocedural hemorrhage, sudden cardiac death, flap failure, aspiration, delirium, and urinary tract infection (UTI) were rare, affecting fewer than ten patients in each group. Due to their low incidences, these complications did not provide sufficient data for risk ratio calculations.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eOur study focused on identifying ESRD as an independent cause of postoperative morbidity and mortality, as limited data exists on this subject. During the 30-day postoperative period, patients with ESRD had significantly higher rates of DVT, MI, pneumonia, anemia, skin graft-related complications, fluid overload, and mortality. The effect of ESRD on DVT and MI risks may be explained by endothelial dysfunction caused by chronic kidney disease, which may lead to thrombotic events [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The mechanisms of a prothrombotic state in ESRD remain unclear, but previous studies have shown that venous thromboembolism events are doubled in this population [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Biben et al. reported that a hypercoagulable state is not a contraindication for free flap procedures but advised the use of a thromboprophylaxis regimen [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The higher rate of postoperative pneumonia in the ESRD cohort aligns with previous studies, which show that patients with chronic renal failure are inherently immunocompromised and are therefore more prone to infection [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. These patients may be more susceptible to developing pneumonia both from in-hospital microbial exposures or from aspiration.\u003c/p\u003e\u003cp\u003eFluid overload is a common issue faced by patients with ESRD. Persistent fluid overload can lead to hypertension, pulmonary edema, and congestive heart failure, increasing the risk of mortality [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Similarly, fluid overload intraoperatively and on postoperative day one have been shown to increase complication rates after microvascular surgery [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Fluid overload in the immediate perioperative period poses a significant threat to flap viability [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. During lengthy surgeries such as H\u0026amp;N free flap reconstruction, intraoperative fluid management may be particularly difficult in patients with severely reduced or no renal function. Lack of urine output may make postoperative fluid balance monitoring difficult between dialysis treatments. Efforts to maintain net zero fluid status may be influenced by institutional or surgeon-based preferences regarding use of vasopressors versus volume replacement in response to changes in vital signs. Postoperative anemia in patients with ESRD is influenced by reduced erythropoietin production [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. H\u0026amp;N free flap reconstructive surgeries may lead to significant intraoperative blood loss, and patients with renal dysfunction are less equipped to restore red blood cell volume. There is data which shows that this postoperative anemia in ESRD patients directly affects mortality [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAn unexpected finding from this study was that patients in the non-ESRD group were significantly more likely to be re-admitted during the 30-day postoperative period. This result differs from reports that ESRD patients typically have higher rates of readmission compared to the general population [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. One important data point that was unavailable to us in this study was length of admission after surgery. It is possible that, with the higher rate of significant complications, ESRD patients remained in the hospital for longer than the non-ESRD patients. This would be corroborated by the findings of Manrique and colleagues [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Earlier discharge may allow for more opportunity for re-admission during this time. Data is not available regarding whether certain patients in our cohorts were transferred to subacute or long-term acute care facilities after hospitalization and if that may have influenced readmission rates.\u003c/p\u003e\u003cp\u003eIn our study, flap failure was a rare occurrence in both cohorts. However, this was only able to be extrapolated upon by identifying patients who required a second free tissue transfer during the 30-day postoperative window. This demonstrates an inherent challenge of using TriNetX as there is no unique ICD 10 code for free flap failure. By using a surrogate grouping of codes, we may have underestimated or overestimated the number of flap failures. Existing literature shows mixed results on free flap success rates in patients with ESRD. Oglesby et al found that, when compared to matched controls, there was a significantly increased risk of flap failure in CKD patients as well as a significantly increased risk of overall complications [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. This study evaluated a relatively small cohort, controlled for few variables such as flap type, age, gender, and cancer stage, and did not control for other medical comorbidities. Manrique et al. also found that ESRD patients were at higher risk of postoperative complications, 30-day mortality, and longer hospital stays, likely due to comorbidities like peripheral vascular disease (PVD) and diabetes [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Our finding was similar to Hung et al., who showed that there was no difference in take-back rates, or reoperation rate, between dialysis and non-dialysis patients in their study [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAlthough we performed propensity matching for multiple comorbidities in attempt to identify ESRD as an independent risk factor, different causes of ESRD itself may have influenced outcomes. For example, Moran et al. found that patients with renal failure associated with diabetes had significantly higher complication rates after free tissue transfer than ESRD patients without diabetes (93% vs. 20%) [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. While renal disease itself seems to be associated with increased complication rates after H\u0026amp;N reconstruction, it may be that the interplay of ESRD and the underlying causative condition(s) may also be important. Future studies should include patients with different stages of chronic kidney disease or should specify dialysis dependency to assess their distinct impacts on free flap outcomes and complications. In addition, future prospective studies are needed to validate these findings and could provide more granular data on the impact of intraoperative fluid management and dialysis scheduling on free flap outcomes.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eOur study demonstrated that ESRD is an independent risk factor for DVT, MI, pneumonia, anemia, skin graft-related complications, fluid overload, and mortality during the 30-days postoperative period after H\u0026amp;N free flap reconstruction. For unclear reasons, readmission rates were higher among patients without ESRD. Prospective data will be important to corroborate and provide further understanding regarding these findings.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eCompeting Interests:\u003c/p\u003e\n\u003cp\u003eThe authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.\u003c/p\u003e\n\u003cp\u003eFunding Statement:\u003c/p\u003e\n\u003cp\u003eThe authors received no financial support for the research, authorship and/or publication of this article.\u003c/p\u003e\n\u003cp\u003eEthical Approval and Informed Consent Statement:\u003c/p\u003e\n\u003cp\u003eThe ethics review committee of Stony Brook Medicine waived the need for ethics approval and patient consent for the collection, analysis and publication of the retrospectively obtained and anonymized data for this non-interventional study.\u003c/p\u003e\n\u003cp\u003eData Availability Statement:\u003c/p\u003e\n\u003cp\u003eThe datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003eAuthor Contributions:\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Data analysis was performed by anonymous. All authors contributed to the writing of the manuscript, and all authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGabrysz-Forget F, Tabet P, Rahal A, Bissada E, Christopoulos A, Ayad T Free versus pedicled flaps for reconstruction of head and neck cancer defects: a systematic review. [published online March 14, 2019]. J Otolaryngol \u0026ndash; Head Neck Surg \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s40463-019-0334-y\u003c/span\u003e\u003cspan address=\"10.1186/s40463-019-0334-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJeong B, Lynch N, Hodge J, Boase S, Valentine R, Krishnan S, Foreman A Single service otolaryngology head and neck surgery free flap reconstruction of head and neck ablative defects \u0026ndash; a retrospective single centre review of our initial 6-year experience. [published online January 26, 2024]. 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Plast Reconstr Surg 113:2006\u0026ndash;2011\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-plastic-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejps","sideBox":"Learn more about [European Journal of Plastic Surgery](https://link.springer.com/journal/238)","snPcode":"238","submissionUrl":"https://submission.nature.com/new-submission/238/3","title":"European Journal of Plastic Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Head and neck cancer, Free flap reconstruction, Outcome studies, Complications, Head and neck reconstruction","lastPublishedDoi":"10.21203/rs.3.rs-7808587/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7808587/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRelatively little data exists regarding the ways in which end-stage renal disease (ESRD) affects microvascular surgery outcomes. This study sought to identify whether ESRD was an independent predictor of 30-day postoperative complication and readmission rates after head \u0026amp; neck free flap reconstruction.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe TriNetX database was used to identify individuals who underwent head and neck free flap reconstruction between 2014 and 2023. Two cohorts were created based on whether or not patients had ESRD. Propensity score matching based on demographics and relevant comorbidities was performed. Differences in 30-day complication and readmission rates were then compared between cohorts.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAfter propensity matching was performed, ESRD patients were noted to have significantly higher risks of deep vein thrombosis (aRR 2.308, \u003cem\u003ep\u003c/em\u003e = 0.008), myocardial infarction (aRR 2.005, \u003cem\u003ep\u003c/em\u003e = 0.045), pneumonia (aRR 1.897, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001), anemia (aRR 1.452, \u003cem\u003ep\u003c/em\u003e = 0.011), skin graft-associated complications (aRR 2.900, \u003cem\u003ep\u003c/em\u003e = 0.002), fluid overload (aRR 1.862, \u003cem\u003ep\u003c/em\u003e = 0.043) and mortality (aRR 2.200, \u003cem\u003ep\u003c/em\u003e = 0.030). Compared to controls, ESRD patients had a lower likelihood of readmission (aRR 0.630, \u003cem\u003ep\u003c/em\u003e = 0.024).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study demonstrated that ESRD can significantly influence several early postoperative outcomes of head and neck free flap surgery when controlling for demographics and other comorbidities.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLevel of Evidence: \u003c/strong\u003eLevel III, risk study\u003c/p\u003e","manuscriptTitle":"Postoperative Morbidity and Mortality in Patients with End-Stage Renal Disease Undergoing Free Flap Reconstruction of the Head and Neck","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-31 01:39:20","doi":"10.21203/rs.3.rs-7808587/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-11-23T18:09:43+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-20T05:44:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"321520738118114633441414559980854954018","date":"2025-10-19T16:02:12+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-17T15:50:27+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-09T03:49:04+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-09T03:47:59+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Journal of Plastic Surgery","date":"2025-10-08T13:45:12+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-plastic-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejps","sideBox":"Learn more about [European Journal of Plastic Surgery](https://link.springer.com/journal/238)","snPcode":"238","submissionUrl":"https://submission.nature.com/new-submission/238/3","title":"European Journal of Plastic Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"0f8e1d5f-2380-4ea7-b8de-b4004eab0e3e","owner":[],"postedDate":"October 31st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-02T16:11:12+00:00","versionOfRecord":{"articleIdentity":"rs-7808587","link":"https://doi.org/10.1007/s00238-026-02400-2","journal":{"identity":"european-journal-of-plastic-surgery","isVorOnly":false,"title":"European Journal of Plastic Surgery"},"publishedOn":"2026-02-25 15:57:29","publishedOnDateReadable":"February 25th, 2026"},"versionCreatedAt":"2025-10-31 01:39:20","video":"","vorDoi":"10.1007/s00238-026-02400-2","vorDoiUrl":"https://doi.org/10.1007/s00238-026-02400-2","workflowStages":[]},"version":"v1","identity":"rs-7808587","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7808587","identity":"rs-7808587","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}